Implantable medical devices (IMDs) such as pacemakers and implantable cardioverter defibrillators are utilized in monitoring and regulating various conditions within the body. An implantable cardioverter defibrillator, for example, may be utilized in cardiac rhythm management applications to monitor the rate and rhythm of the heart and for delivering various therapies such as cardiac pacing, cardiac defibrillation, and/or cardiac therapy. The implantable medical device can communicate with other medical devices implanted within the body tasked to sense various physiological parameters occurring within the body. For example, one or more remote sensors may be located deep within the body for monitoring parameters such as temperature, pressure, strain, fluid flow, chemical properties, electrical properties, magnetic properties, and the like. Based on the measurements received from the remote sensor, the implantable medical device may then deliver an appropriate treatment to the patient.
Communication between implantable medical devices and remote sensors is sometimes accomplished via an acoustic telemetry link. An acoustic transducer on the remote device can be configured to receive an acoustic signal transmitted by the implantable medical device, from another device inserted within the body, or from an external device located outside of the patient's body. The acoustic energy from the signal can be configured to establish an acoustic telemetry link that can be utilized for communicating between the devices, to energize or power the remote device, or both.
In some systems, an acoustic wake-up circuit can be used to transition the remote device from an inactive, low-power state into an active state. The acoustic wake-up circuit can be connected to an acoustic transducer, which converts an acoustic wake-up signal received into an electrical signal that can be passed along to the wake-up circuit. An example acoustic wake-up switch that can used in such systems is described in U.S. Pat. No. 6,628,989, entitled “Acoustic Switch and Apparatus and Methods For Using Acoustic Switches Within A Body,” which is incorporated herein by reference in its entirety.